Fuel Tank Vent Warning
 

I been meaning to share this for a while, but just now have the chance.
Last winter we drove my '83 300D from Vermont to North Carolina. No problems, it was a great ride. However, on the way home, we got stuck in the middle of The Fort McHenry tunnel on I95. The car just died, and I have to say that being trapped there with my family was one of the most terrifying experiences of my life.
Long story short, some kind soul called the tunnel authority on their cell phone and we were quickly rescued by the State Police and a tow truck.
When we got out of the tunnel I checked the primary filter -no fuel! That was weird considering that my fuel gauge was at 1/2. I tried to put fuel in the tank, but it would only take 0.8 gal.
After a little more checking, I realized that my fuel tank had imploded like a crushed beer can reducing its capacity and jamming the fuel sender at the 1/2 mark.
Culprit was the tank vent, which for some reason is located under the car just ahead on the drivers side right rear wheel. It was completely jammed with dirt and I imagine vacuum created by sucking fuel from the tank was what caused the implosion.
Please do yourself a favor and check/clean your vent before it's too late. At the least you could save yourself an expensive repair.

I was wondering what that was . It looks like a bell, right ? I'll check mine this morning as I was down at my land on dirt roads when it rained.

Yes it looks like a bell.
I cleaned mine out with a large syringe, so that I could push and pull air through it. It took a while, but eventually it came clean.

Checking and cleaning that vent probably should be a once in awhile occurance. Unless there is no vaccum equilization noise when removing the filler cap after a long highway run.
Your experience was extreme and costly. I suspect from the tank implosion that your lift pump is in pretty good condition though.:)
I have a pretty good 1984 300d with 159k perhaps even original miles as interior does not even look like anyone has even sat in it. All because of an obstructed vent. For five hundred american to the garage owner it turned into a great deal.
When the car quit on the highway the owner cranked till he burnt out the starter. The car was towed to a pretty knowledgeable garage. They quoted him 600.00 to change the starter out. Plus told him he may even need an injection pump. The owner then walked away from the car.
When I examined the non running car I asked the mechanic why he had come to that conclusion. He told me they had changed four injection pumps out on this model in the last couple of months that had been burning vegatable oil or bio diesel. Our first bio diesel in our area was a disaster.
In otherwords he had let his current experience bias overcome the reality as it turned out. I was also prepared to change the injection pump if it was bad as well.
Anyways after a very long time I got a new ownership through the courts at no charge. Had the car flatbedded home. Removed and repaired the starter. Drained the vegatable oil out. Cleaned the vent. Put some diesel in and started it up. Ran great other than too much blowby.
I suspect the rings are gummed from the unheated vegatable oil the previous owner used. Will get around to soaking it down with marvel mystery oil one of these days.
I can hardly wait until people start burning unheated vegatable oil in the newer diesels. :D You lost a fuel tank perhaps and some money from an obstructed vent. Plus the real scary experience of having the car die in a tunnel. The previous owner of my car basically just lost his car.
So it does pay to clean that vent periodically. Especially if there is any indication at all.
The reason perhaps the previous owner might have missed the swoosh from the tank neck everytime he fuelled. He might have considered the noise of no consequence.
So if you are starting to hear a noise of the tank vacuum being equalized when fuelling take a little time and clean the vent. It does not obstruct overnight usually. It will probably affect your performance as the fuel level drops to some degree before becoming bad enough to make your car quit. It also makes your lift pump strain to deliver fuel as long as it can.
It also is far more likely to quit out on the highway with a bad vent when running steadily in a high flow constant fuel requirement situation. This is just one simple thing that is avoidable and cheap to prevent happening. The car even tells you that it's on the way if you pay attention.
Farmer it was a really good ideal in my opinion to post this as very little to nothing has been posted as a preventative type of thing that I am aware of. All the previous posts have just dealt with finding the problem basically after the fact. .

Can someone post a pic or link to a pic of the bell shaped vent? I don't think I saw anything resembling it last time I followed the fuel lines from the engine to the tank. I am not sure if everything is originalnthough. On mine, there are short sections of metal and rubber hose pieces spliced in with aftermarket hose clamps from the tank making it's way down before the long horizontal runs to the engine compartment.

It's near the left rear tire. It's closer to the side than the fuel lines but you can still trace it from where the fuel lines come out of the tank under the car.
There are 3 lines. Fuel, fuel return and the vent line.

Danny